I am loving the direction of the new asset canisters.
I wanted to point out though that the way the new asset canister build process is designed still seems to be very specific to Webpack. For context, I have been spending quite a few hours over the past couple days trying to get dfx build/dfx deploy to work with bundlers that are not Webpack. I have been experimenting with my own bundler Zwitterion and with Snowpack (both of which rely heavily on native ES modules and eschew traditional bundling to use the platform as much as feasible). Neither of them work out of the box, and I have been trying many workarounds but still have not gotten a full frontend up and running that can communicate with a canister.
I have opened a couple forum posts that will help, but I have a suggestion I think could really inform the dfx build process: When developing the build process, create non-trivial example projects using a variety of build techniques including Webpack, Parcel, Snowpack, no bundler, etc.